EP3164225B1 - System and method for applying a viscous medium to a surface - Google Patents

Description

The invention relates to a module, a system and a method for applying a viscous medium to a surface, and a method for producing the module.

A module for applying a viscous medium to a surface of a workpiece is described, for example, in the publication WO 2009/144295 A1 described. The module described there is designed as a slot die which has a reservoir with a slot and a closing mechanism. The slot can be opened and closed by means of the closing mechanism in order to precisely switch a mass flow of the viscous medium through the slot on and off. However, due to the locking mechanism, such slot dies are relatively expensive and require extensive cleaning after use.

It is therefore the object of the present invention to propose a module for applying a viscous medium to a surface which can be manufactured and handled as simply as possible. Furthermore, a manufacturing process for such a module, which is as simple and inexpensive as possible, and a method for applying a viscous medium using such a module, as well as a system with such a module, are also proposed.

This object is achieved by a method according to the main claim and by a system according to the secondary claim. Preferred embodiments and further developments result from the remaining claims.

The module also proposed here for applying a viscous medium to a surface is used in carrying out the method according to the invention and is also contained in the system according to the invention. The surface mentioned here and below can be, for example, a surface of any substrate to which the viscous medium can be applied, such as the surface of a workpiece, a component or a die. The viscous medium mentioned here and below can be, for example, an adhesive, a paint or a lacquer, such as a curable lacquer for producing a microstructure. Further examples and information regarding the viscous medium and the surface follow below.

The module has a reservoir that can be fed (filled) with the viscous medium, for example via media connections of the module designed for this purpose. The reservoir can be a cavity in the module, for example. The reservoir is preferably cylindrical so that the most uniform possible overpressure (measured relative to the ambient pressure, typically therefore relative to the atmospheric pressure) can be produced in the reservoir when the viscous medium is applied. A uniform overpressure favors an even media discharge from the reservoir. For the same reason, the module can have two or more equally spaced media connections for feeding the reservoir, which, for example, at opposite ends of the Reservoirs are arranged. The overpressure in the reservoir required for the application of the medium is, as will be explained in more detail below, typically produced and controlled or regulated exclusively by conveying the medium to be applied into the reservoir. In addition, the media discharge through the nozzle channels is typically caused exclusively by the excess pressure. In contrast, centrifugal forces caused by rotating the module around its longitudinal axis are irrelevant. Typically, there is no rotation of the module about its longitudinal axis during the media discharge from the reservoir, so that centrifugal forces therefore neither effect nor significantly influence the media discharge. Typically, the module is fixed in a rotationally fixed manner with respect to its longitudinal axis during media discharge.

The outer surface (ie the outer surface) of the module includes an outlet area for the viscous medium, which typically extends along an entire longitudinal extent of the reservoir, for example along a longitudinal axis of the reservoir. The module has at least one nozzle channel, that is to say either exactly one nozzle channel or several nozzle channels. In the following, for the sake of brevity and clarity, sometimes "instead of" the at least one nozzle channel "simply" the nozzle channel "is said, but what is said still refers to" the at least one nozzle channel ", that is to all nozzle channels in the case of several nozzle channels. If a certain property (such as the smallest diameter, largest diameter, cross-sectional area, channel length, channel profile, flow resistance, etc.) of the at least one nozzle channel is described, then in the case of several nozzle channels, the relevant property of each nozzle channel is meant.

The at least one nozzle channel fluidly connects the reservoir to the outlet area, so that the viscous medium can flow out of the reservoir to the outlet area through the at least one nozzle channel. Starting from the outlet area, the viscous medium can be delivered to the respective surface (for example the substrate, the component or the die, see below). Typically, the outlet area in the direction of the longitudinal axis or the longitudinal extent of the reservoir is not curved, but is designed to be straight or flat, so that the viscous medium can be applied particularly uniformly to a flat surface.

The present invention is based on the finding that it is possible with the aid of the at least one nozzle channel to switch a mass flow of the viscous medium out of the reservoir in a simple and, in most cases, sufficiently precise manner. The at least one nozzle channel has a flow resistance for the viscous medium, which opposes the mass flow of the viscous medium through the at least one nozzle channel and, depending on the size of the excess pressure of the viscous medium within the reservoir, can slow it down or bring it to a complete standstill. The flow resistance is due in particular to the friction of the viscous medium on the channel inner walls of the at least one nozzle channel and also to the internal friction of the medium within the at least one nozzle channel during the outflow of the viscous medium. These friction effects thus cause a relatively high pressure drop within the at least one nozzle channel.

Therefore, in order to generate a mass flow of the viscous medium through the at least one nozzle channel, the viscous medium in the interior of the reservoir must be subjected to an excess pressure which is sufficiently high to overcome the forward resistance of the at least one nozzle channel. If, for example, the delivery of the viscous medium into the reservoir is ended, the overpressure in the reservoir drops relatively quickly to such an extent that the overpressure is no longer sufficient to maintain the mass flow. Therefore, by sufficiently reducing the overpressure within the reservoirs, for example by stopping the conveyance of the viscous medium into the reservoir, the mass flow of the viscous medium through the at least one nozzle channel (and thus also the application of the viscous medium to the surface) can be very abrupt and be finished precisely. Unwanted afterflow after the pressure drop is strongly suppressed and largely prevented by the high flow resistance of the at least one nozzle channel. In the case of conventional wide slot nozzles, an undesired reflow can be caused, for example, by a residual pressure which is still present in the reservoir and / or by gravity (if the slot of the reservoir is oriented downward, for example).

With the help of at least one nozzle channel, the mass flow can also be started very abruptly and precisely. If the pressure is too low initially no mass flow generated. The viscous medium is not discharged from the reservoir through the at least one nozzle channel until, for example, a corresponding conveyance of the viscous medium into the reservoir has produced the (relatively high) excess pressure required for the mass flow.

Advantageously, the module does not have its own closing mechanism and no moving parts for closing or blocking the at least one nozzle channel, such as an (automatic or manually operated) closing mechanism, and can therefore be manufactured particularly easily and inexpensively. As a simple and inexpensive disposable component, the module can be disposed of after use and replaced by a corresponding or identical module. This eliminates the need for time-consuming cleaning of the module, which is often harmful to the environment and which, for example when using organic solvents to remove paint residues, can also necessitate costly protective measures against possible health risks for the personnel. The module can be made of a plastic, for example a plastic that is suitable for producing the module in an injection molding process. The module can thus be designed, for example, as an injection molded part. The group of polyolefins such as polyethylene and polypropylene and also polyamide are suitable as plastics. In addition, the module can consist of several module segments that are assembled axially to form the module. These module segments can comprise, for example, two identical end segments or end caps, which laterally close off the reservoir and which, if appropriate, can each have one of the media connections mentioned. In addition, the module segments can comprise one or more intermediate segments, which can be arranged between the end segments or end caps, laterally delimit the reservoir and have the at least one nozzle channel. The intermediate segments can for example be tubular and each form an axial section of the module (with respect to the longitudinal axis of the module). The module segments can be connected to one another, for example, by means of appropriately designed connecting elements of the module, for example by means of clamping or tensioning elements acting in the axial direction.

The achievable pressure drop in the at least one nozzle channel depends particularly strongly on the smallest diameter of the at least one nozzle channel. As already mentioned above, in the case of a plurality of nozzle channels, each of the nozzle channels has its own smallest diameter. When speaking of the smallest diameter of the at least one nozzle channel, the smallest diameter of each nozzle channel is meant. The same applies in particular to the largest diameter mentioned below and the channel length of the at least one nozzle channel. The smallest diameter of the at least one nozzle channel is typically 0.8 mm or less, for example the smallest diameter can also be less than 0.6 mm to 0.1 mm. In addition, it can be provided that the at least one nozzle channel has a largest diameter, the largest diameter of the at least one nozzle channel being less than 3 mm, preferably less than 2 mm. In the special case of only a single nozzle channel, this preferably extends along the entire longitudinal extent of the reservoir, ie it is designed as a narrow, long slot. The largest diameter of the nozzle channel then corresponds approximately to the total length of the reservoir.

A cross-sectional area of the nozzle channel can be used to define the smallest diameter of a nozzle channel. The cross-sectional area used is preferably oriented perpendicular to the course of the nozzle channel from the reservoir to the outlet area, that is to say perpendicular to a longitudinal extent or a longitudinal axis of the nozzle channel. In general, the smallest diameter can be defined as the diameter of the largest possible circle which lies entirely within the cross-sectional area of the nozzle channel under consideration (ie as the diameter of the largest possible inscribed circle of the cross-sectional area). Accordingly, a largest diameter of a nozzle channel can generally be defined as the diameter of the smallest possible circle that completely contains the cross-sectional area (ie as the diameter of the smallest possible circumscribed circle of the cross-sectional area). In the special case of a circular cross-sectional area, the smallest diameter is equal to the largest diameter and corresponds to the usual diameter of the cross-sectional area. In the case of differently shaped, non-circular Cross-sectional areas, the smallest diameter is smaller than the largest diameter of the respective nozzle channel.

Each of the at least one nozzle channel extends from an inlet opening of the respective nozzle channel with which the nozzle channel opens in the reservoir to an outlet opening of the respective nozzle channel with which the nozzle channel opens in the outlet area on the outer surface of the module. The at least one nozzle channel has a channel length measured from the reservoir to the outlet area, which can be defined as the distance between the respective inlet opening and outlet opening. The channel length is typically 0.8 mm or more, for example 1.6 mm or more.

It is also possible that the at least one nozzle channel has a cross-sectional area that changes along the channel course from the reservoir to the outlet area and narrows or widens, for example, along this course. For example, the at least one nozzle channel can be designed step-like or conical. With cross-sectional areas that are variable in this way, the smallest (or largest) diameter of a nozzle channel is typically defined by the smallest value of the smallest diameter (or by the largest value of the largest diameter) along the entire course of the respective nozzle channel.

It is also necessary for the module to be dimensionally stable enough to withstand the overpressure with which the viscous medium is applied in the reservoir. Typically, depending on the viscosity of the viscous medium and the size of the pressure drop in the at least one nozzle channel, an excess pressure of more than 1.5 bar is used, typically the excess pressure is in a range between 1.5 bar and 30 bar.

The reservoir typically has a length (measured along the above-mentioned longitudinal dimension or longitudinal axis) of more than 10 cm or more than 50 cm. Typically, however, the length is not greater than 100 cm or not more than 150 cm. In the case of a plurality of nozzle channels, the nozzle channels are preferably arranged along the entire longitudinal extent of the reservoir (so that the outlet region extends along the entire length of the reservoir). The distances between adjacent nozzle openings (measured in the direction of the longitudinal axis of the reservoir) are typically in a range between 0.2 mm and 3 mm. The number of nozzle openings per unit length is z. B. at least 100 / m. The greater the number of nozzle channels, the greater the total mass flow through the at least one nozzle channel for a given excess pressure. If the nozzle ducts are designed to be very narrow and with a large duct length in order to enable the highest possible pressure drop and the most controllable switching on and off of the mass flow, an increased total passage at a given excess pressure can be achieved by increasing the number of nozzle ducts.

In order to enable a large number of nozzle channels, the nozzle channels in the outlet area can be arranged, for example, in rows, that is to say in at least one row, the at least one row of the nozzle channels running along the longitudinal extent (or the longitudinal axis) of the reservoir. For example, the nozzle channels can be arranged in two or more rows, these rows preferably running parallel to one another and parallel to the longitudinal extent or longitudinal axis of the reservoir. In order to obtain an arrangement of the nozzle channels that is as uniform and easy to manufacture as possible, it is in particular possible for the nozzle channels in adjacent rows to be arranged offset to one another in the direction of the longitudinal extent of the reservoir. In this way (imaginary) connecting lines of adjacent nozzle channels form a zigzag pattern.

The module has a squeegee edge which runs along the outlet area. The squeegee edge is therefore typically arranged on the outer surface of the module and is therefore on the outside of the module. For example, the squeegee edge can be formed by a partial area of the outer surface of the module. This partial area can be shaped, for example, step-like or edge-shaped. The partial area can adjoin the outlet area. For example, a distance between the nozzle channels and the doctor edge can be between 0 mm and 2 mm. Furthermore, the squeegee edge can have a sharp-edged or rounded shape. If the nozzle channels are arranged in rows, the doctor edge typically runs along or parallel to at least one row of the nozzle channels. By means of the squeegee edge, it is possible to distribute the viscous medium applied to the surface over the surface, for example by suitably relative to the module and the surface during application are moved towards each other. For example, a particularly uniform layer thickness of the viscous medium can be achieved on the surface by means of the knife edge. It is also possible to introduce the viscous medium particularly well into depressions in the surface, if present, for example in the case that the surface is structured, such as in the case of matrices whose surface has a negative shape of a surface structure to be produced, and so on, with the doctor edge is described in more detail below.

• dass das Austragen des viskosen Mediums durch den mindestens einen Düsenkanal aus dem Reservoir des Moduls begonnen und aufrechterhalten wird, indem der Überdruck des viskosen Mediums in dem Reservoir mindestens soweit vergrößert wird, bis der Durchlasswiderstand des mindestens einen Düsenkanals für das viskose Medium überwunden wird (und das viskose Medium durch den mindestens einen Düsenkanal hindurch aus dem Reservoir ausfließt), und
• dass das Austragen des Mediums gestoppt oder unterbrochen wird ohne den mindestens einen Düsenkanal durch Schließelemente oder dergleichen zu versperren, indem der Überdruck des viskosen Mediums innerhalb des Reservoirs mindestens soweit abgesenkt wird, bis der Durchlasswiderstand des mindestens einen Düsenkanals für das viskose Medium nicht mehr überwunden wird (und das Hindurchfließen des viskosen Mediums durch den mindestens einen Düsenkanal durch den Druckverlust des viskosen Mediums in dem mindestens einen Düsenkanal gestoppt wird).

In the method according to the invention, a viscous medium is applied to a surface using the module described here. The process is characterized by

• that the discharge of the viscous medium through the at least one nozzle channel from the reservoir of the module is started and maintained by increasing the positive pressure of the viscous medium in the reservoir at least until the flow resistance of the at least one nozzle channel for the viscous medium is overcome (and the viscous medium flows out of the reservoir through the at least one nozzle channel), and
• that the discharge of the medium is stopped or interrupted without blocking the at least one nozzle channel by closing elements or the like, by reducing the excess pressure of the viscous medium within the reservoir at least until the flow resistance of the at least one nozzle channel for the viscous medium is no longer overcome (and the flow of the viscous medium through the at least one nozzle channel is stopped by the pressure loss of the viscous medium in the at least one nozzle channel).

Typically, with the discharge of the medium from the reservoir, the application of the viscous medium to the surface is started and maintained or stopped, practically simultaneously. In the method, the at least one nozzle channel is therefore not opened or closed in order to begin or end the application of the viscous medium. Rather, the at least one nozzle channel is kept in an open state during the entire process. The method is therefore carried out without the mass flow of the viscous medium through the at least one nozzle channel by means of movable closing elements on the to influence at least one nozzle channel. After the method has been carried out, the cleaning of such locking elements is therefore also eliminated.

An adhesive, a paint or a lacquer, in particular a curable lacquer for producing a microstructured surface, for example a dual-cure lacquer, can be used as the viscous medium. The viscous medium used typically has a (dynamic) viscosity of 0.5 Pa · s or more. The viscous medium therefore has a relatively low flowability and can be present, for example, as a paste. As a rule, however, the viscosity is not more than 150 Pa · s.

The proposed method is suitable for producing a microstructured surface, for example on that in the document WO 2013/083682 A1 or DE 103 46 124 B4 and in the associated late registration WO 2005/030472 A1 described way.

According to the terminology of the latter publications, a microstructured surface is understood to mean a surface which has a microstructure, that is to say a surface topography, which essentially has structures in the range from 100 μm to 0.5 μm, preferably 50 μm to 0.5 μm , Distance and depth. The microstructure can be a so-called riblet structure, for example, which can comprise, for example, rib-shaped or web-shaped elevations. Riblet structures can bring about a reduction in frictional resistance on turbulent surfaces, and thus become, for example on surfaces of aircraft, rail vehicles, ships, in particular the surfaces of their fuselages, and / or wind energy plants, in particular the surfaces of their rotor blades.

The microstructure is produced by molding (e.g. embossing) using a die, as described below. The error in the impression (deviation from the target shape) is typically less than 5 μm, preferably less than 1 μm. According to the invention, a microstructure is produced on a surface of a component by molding a die which has a negative (ie a negative shape) of the microstructure to be produced. The die is preferably flexible in shape in order to be able to adapt to curvatures of the respective component surface. The viscous medium can be applied to the negative of the die using the module and then to the component surface using the die. Alternatively, it is also possible to apply the viscous medium directly to the component surface and then to bring the applied viscous medium into contact with the die. In both cases, a layer of the viscous medium is generated on the component surface and the die with the negative is pressed onto the component surface, for example by means of the above-mentioned pressure roller, so that the microstructure to be produced is transferred to the layer by molding using the negative of the die. Here, the layer of the viscous medium is located between the component surface and the negative of the die. For example, the roller can be rolled over the surface in such a way that the die moves between the roller and the surface in a rolling movement, so that the negative of the die faces the surface. The die can be designed as a band or strip, in particular as an endless band.

Typically, the layer formed from the viscous material is fully or at least partially cured even while it is between the die and the component surface, that is to say in situ , in order to stabilize the layer and the microstructure produced on it. In order to accelerate the hardening, the above-mentioned device for accelerating the hardening can be used, which can have, for example, a (UV) radiation source or a heat source. After the viscous material in the layer has hardened sufficiently, the die can be removed from the component surface without the microstructure runs in the layer of the (originally viscous) medium or the layer detaches from the component surface. This removal can take place, for example, by moving (unrolling) the pressure roller and / or a further roller on the component surface.

In this way, the component surface can be provided with the microstructure continuously or discontinuously along a practically arbitrarily long path, with the material discharge from the reservoir being simply and precisely reduced by reducing the overpressure in order to end the path or to generate an interruption in the microstructure in the course of the path can be terminated or interrupted in the reservoir as described above. At the start of a new route or to continue the microstructure along a route that has already started, the excess pressure required for discharge can be generated again in order to continue the material discharge. After the component surface has been coated or if there is to be a long interruption in the process, the module can be replaced by a further, still unused module of the type proposed here.

The system according to the invention is suitable for applying a viscous medium to a surface and in particular for carrying out the method proposed here. All the features described in connection with the method can therefore also be correspondingly transferred to the proposed system. The system comprises the module described here as well as a conveyor device which can be fluidly connected to the module and which is set up to convey the viscous medium into the reservoir of the module and to apply the excess pressure already described there. The overpressure of the viscous medium in the reservoir, which can be generated by means of the conveying device, is so great that the viscous medium to which the overpressure is applied flows out of the reservoir through the at least one nozzle channel. The system therefore generally does not have a (automatic or manually operated) closing mechanism which is arranged on the at least one nozzle channel and which would be set up to open and close the at least one nozzle channel.

• zum Starten eines Auftragevorgangs und zum Aufrechterhalten des Auftragevorgangs die Fördervorrichtung so anzusteuern, dass die Fördervorrichtung das viskose Medium innerhalb das Reservoirs mit dem genannten Überdruck zu beaufschlagen, und
• zum Stoppen oder Unterbrechen des Auftragevorgangs die Fördervorrichtung so anzusteuern, dass die Fördervorrichtung den Überdruck des viskosen Mediums innerhalb des Reservoirs soweit absenkt, dass der genannte Durchlasswiderstand des mindestens einen Düsenkanals das Ausströmen des viskosen Mediums durch den mindestens einen Düsenkanal stoppt. Dieses Absenken des Überdrucks kann beispielsweise durch einen Stoppen der Förderung des viskosen Mediums in das Reservoir durch die Fördervorrichtung erzielt werden, beispielsweise durch ein Aus- oder Inaktivschalten der Fördervorrichtung, oder durch ein Schließen eines steuerbaren Auslassventils der Fördervorrichtung. Insbesondere wird aber kein an dem mindestens einen Düsenkanal angeordneter Schließmechanismus zum Verschließen des mindestens einen Düsenkanals betätigt oder entsprechend angesteuert.

The conveyor can be controllable. The system may further comprise a control unit for controlling the conveyor device, the control unit being connected and set up for transmitting control signals to the conveyor device,

• in order to start an application process and to maintain the application process, to control the conveying device in such a way that the conveying device acts on the viscous medium within the reservoir with the above-mentioned overpressure, and
• To stop or interrupt the application process, control the conveying device in such a way that the conveying device lowers the excess pressure of the viscous medium within the reservoir to such an extent that the flow resistance of the at least one nozzle channel stops the viscous medium from flowing out through the at least one nozzle channel. This lowering of the excess pressure can be achieved, for example, by stopping the delivery of the viscous medium into the reservoir by the delivery device, for example by switching the delivery device off or inactive, or by closing a controllable outlet valve of the delivery device. In particular, however, no closing mechanism arranged on the at least one nozzle channel for closing the at least one nozzle channel is actuated or controlled accordingly.

• eine Matrize mit einem Negativ der zu erzeugenden Mikrostruktur, wie oben beschrieben, wobei die Matrize und das Modul so angeordnet sind, dass das viskose Medium mittels des Moduls auf das Negativ der Matrize oder direkt auf die Bauteiloberfläche aufgetragen wird,
• eine über die Bauteiloberfläche abrollbare Andruckwalze zum Andrücken der Matrize auf die Bauteiloberfläche, wobei Andruckwalze und Matrize so angeordnet sind, dass beim Abrollen der Walze über die Bauteiloberfläche die Matrize in einer rollenden Bewegung zwischen Walze und Oberfläche gelangt, so dass das Negativ der Matrize der Oberfläche zugewandt ist.

The system is designed to carry out the method proposed here for producing a microstructure on a component surface. The system therefore also includes:

• a die with a negative of the microstructure to be produced, as described above, the die and the module being arranged in such a way that the viscous medium is applied by means of the module to the negative of the die or directly to the component surface,
• a pressure roller that can be rolled over the component surface for pressing the die onto the component surface, the pressure roller and die being arranged in such a way that when the roller rolls over the component surface, the die passes between the roller and the surface in a rolling movement, so that the negative of the die of the surface is facing.

The system can also have all the features described in connection with the proposed method. The system can also be used as a tool in DE 103 46 124 B4 and WO 2005/030472 A1 proposed Be designed and have each of the features described there. Accordingly, the method and system proposed here can be designed in such a way that it enables the microstructuring of double-curved component surfaces, preferably on large structures such as aircraft, rail vehicles, ships, in particular their hulls, and / or wind turbines, in particular their rotor blades.

For example, the system can be moved relative to the surface to which the viscous medium is to be applied. Typically, this movement is a relative displacement between the module and the surface, typically there is no rotation of the module about its longitudinal axis (at least no rotation that influences the media discharge from the reservoir). This can be done, for example, manually or via the system's own drive, wherein the system can include driven wheels, for example. The system can be designed as a mobile coating system which is set up, for example, for applying adhesives for carpets on construction sites or for applying paints and varnishes. It is also possible for the system to be moved along the respective surface by means of a robot arm, in particular in the case of the production of microstructures on component surfaces already described, in particular in the case of the Riblet application. However, the system can also be stationary, so that the surface to which the viscous medium is to be applied is moved relative to the system, for example relative to the outlet area of the module and / or to the die described above. The system can also be a stationary coating system for batch production, such as a desk coater. The system typically has a holder for the module, by means of which the module is fixed in a rotationally fixed manner with respect to its longitudinal axis during the media application.

In the method proposed here for producing a module of the type proposed here, a plastic which is suitable for processing in an injection molding process is injected into a mold in a flowable state. The molding tool is designed as a negative form of the module and can comprise, for example, a die, also referred to as a die part, and a core. The die, which can be constructed in one or more parts, has an interior which is a negative shape of the outer surface of the module. The core, too can be constructed in one or more parts is a negative form of the reservoir of the module. The core or the die also have at least one pin or web, which are designed as negative forms of the at least one nozzle channel of the module. For example, the die can be designed such that it also has an area with a negative shape of the doctor edge, if such is provided. Then the knife edge can also be produced by the injection molding process at the same time. The negative shape of the squeegee edge can, for example, be configured as a channel-shaped or slot-shaped depression on an inner surface of the die. The squeegee edge is then a partial area of the injection molded part, and therefore consists of the same plastic as the rest of the injection molded part.

Figur 1:

ein Modul hier vorgeschlagener Art in einer perspektivischen Ansicht,

Figur 2:

eine Ansicht eines Querschnitts durch das in der Figur 1 gezeigte Modul entlang der in Figur 1 gezeigten Schnittlinie,

Figur 3:

einen stark vergrößerten Teilbereich von Figur 2,

Figur 4A:

eine Querschnittsfläche eines Düsenkanals mit länglicher Querschnittsfläche eines Moduls hier vorgeschlagener Art,

Figur 4B:

einen Längsschnitt durch einen sich konisch verengenden Düsenkanal eines Moduls hier vorgeschlagener Art,

Figur 4C:

einen Längsschnitt durch einen sich stufenförmig verengenden Düsenkanal eines Moduls hier vorgeschlagener Art,

Figur 5:

das in Figur 1 gezeigte Modul in einer Seitenansicht,

Figur 6A:

einen stark vergrößerten Teilbereich von Figur 5,

Figur 6B:

der in Figur 6A gezeigte Teilbereich für eine zweireihige Anordnung der Düsenkanäle,

Figur 7:

eine Seitenansicht eines Systems hier vorgeschlagener Art mit dem in Figuren 1 bis 3 gezeigten Modul und

Figur 8:

eine Ansicht eines Querschnitts durch ein Formwerkzeugs hier vorgeschlagener Art zum Herstellen des in Figuren 1 bis 3 gezeigten Moduls.

The invention is explained in more detail below on the basis of a few specific exemplary embodiments, some of which are shown in FIGS Figures 1 to 8 are shown schematically. It shows:

Figure 1:

a module proposed here in a perspective view,

Figure 2:

a view of a cross section through the in the Figure 1 module shown along the in Figure 1 shown cutting line,

Figure 3:

a greatly enlarged section of Figure 2 ,

Figure 4A:

2 shows a cross-sectional area of a nozzle channel with an elongated cross-sectional area of a module of the type proposed here,

Figure 4B:

2 shows a longitudinal section through a conically narrowing nozzle channel of a module of the type proposed here,

Figure 4C:

3 shows a longitudinal section through a step-wise narrowing nozzle channel of a module of the type proposed here,

Figure 5:

this in Figure 1 shown module in a side view,

Figure 6A:

a greatly enlarged section of Figure 5 ,

Figure 6B:

the in Figure 6A partial area shown for a two-row arrangement of the nozzle channels,

Figure 7:

a side view of a system proposed here with the in Figures 1 to 3 module shown and

Figure 8:

a view of a cross section through a mold proposed here for producing the in Figures 1 to 3 shown module.

In the figures, recurring reference symbols designate the same or corresponding features. The figures do not represent true-to-scale illustrations, but serve as simplified, schematic representations for illustration purposes only.

In Figure 1 a perspective view of a module 1 of the type proposed here for applying a viscous medium to a surface is shown. The surface can be, for example, a surface of a component or a die, as in Figure 7 is shown. The viscous medium can be, for example, a curable lacquer, such as a dual-cure lacquer for producing a riblet structure on a component surface, as will be described in more detail below.

In Figure 1 a reservoir 2 of the module 1 for the viscous medium is drawn in with a broken line. The module 1 has two media connections 3 for feeding the reservoir 2 with the viscous medium, which are arranged at opposite ends of the reservoir 2, see also Figure 5 .

Like in that Figures 2 and 3 Cross section of the module 1 shown (the associated section line AA is in Figure 1 is shown), the reservoir 2 is configured in this example as a cylindrical cavity in the module 1. The outer surface 4 of the module 1 comprises a flat outlet area 5 for the viscous medium, which extends along a longitudinal axis L of the reservoir 2, see Figure 1 , extends. The module 1 also has a plurality of nozzle channels 6, which each fluidly connect the reservoir 2 to the outlet area 5, see also Figure 5 . A doctor edge 7 of the module 1 is arranged adjacent to the outlet area 5.

The module 1 has no closing mechanism and no moving parts for closing or blocking the nozzle channels 6. As below based Figure 8 is described, the module 1 is a simple and inexpensive to produce injection molded part that is intended as a disposable component. In the present example, the module consists of several module segments that have been assembled axially. Two end caps 8 close off the reservoir 2 at the end and carry the lateral media connections 3. Between the two end caps 8 there is an intermediate segment 9, which laterally delimits the reservoir 2 and has the nozzle channels 6. Instead of only one intermediate segment 9, the module 2 could also have a plurality of intermediate segments 9 of the same type and axially connected to one another in order to achieve a correspondingly greater overall length of the module. The module segments 8, 9 are connected to one another by connecting elements (not shown here), for example by clamping or tensioning elements acting in the axial direction.

The forward resistance of the nozzle channels 6 for the viscous medium depends particularly strongly on the smallest diameter d _{min of} the nozzle channels 6 and also on their length I. In the present example, the nozzle channels 6 have an equally large, circular cross-sectional area over their entire length I. that the smallest diameter d _min corresponds to the usual diameter of the nozzle channel 6, see Figure 3 . In the present example, the smallest diameters d _{min are,} for example, 0.8 mm and the lengths I of the nozzle channels are, for example, 1 mm. Each of the nozzle channels 6 extends from an inlet opening 10 of the respective nozzle channel 6, with which the nozzle channel 6 opens into the reservoir 2, to an outlet opening 11 of the respective nozzle channel 6, with which the nozzle channel 6 opens into the outlet area 5 on the outer surface 4 of the module 1 . The nozzle channels 6 each have a channel length I measured from the reservoir 2 to the outlet area 5. In this example, the channel lengths I are 1 mm each.

As in Figure 4A is shown, the nozzle channels 6 can also have, for example, an elongated, in this case an oval, cross-sectional area instead of a circular cross-section. Here, the smallest diameter d _{min is,} for example, 0.5 mm and the largest diameter d _{max is} 2 mm, which are defined as the diameter of the largest possible inscribed circle K ₁ or as the diameter of the smallest possible inscribed circle K ₂ .

As in Figures 4B and 4C is shown, it is also possible for the nozzle channels 6 to have cross-sectional areas that change along their channel course from the reservoir 2 to the outlet area 5 and that narrow or widen, for example, along this course. For example, the in narrows Figure 4B shown nozzle channel 6 conical to the outlet opening 11 and there has a smallest diameter d _min of 0.5 mm. The in Figure 4C The nozzle channel 6 shown narrows in a step-like manner towards the outlet opening 11 and there has a smallest diameter d _min of 0.6 mm.

In Figure 5 is that in Figure 1 The module 1 shown is shown again in a side view, in which the nozzle channels 6 in the outlet area 5 and the doctor edge 7 can also be seen. It can also be seen that the nozzle channels 6 are arranged in a row which runs parallel to the doctor edge 7 and to the longitudinal axis L of the reservoir 2. The distance between two adjacent nozzle channels 6 (measured along the longitudinal axis L) is 0.2 mm in this example. This is also enlarged in Figure 6A shown. In Figure 6B An alternative arrangement of the nozzle channels 6 is shown, in which the nozzle channels 6 are arranged in two rows running parallel to the longitudinal axis L and axially offset from one another (connecting lines between the nozzle channels 6 would form a zigzag pattern). In this way, for example, with the same axial distance between the nozzle channels 6, a twice as large number of nozzle channels can be achieved, so that with the same overpressure, a twice as large total mass flow of the viscous medium can be generated from the reservoir 2. For example, the reservoir 2 has a length (measured along the longitudinal axis L) of 50 cm. The nozzle channels 6 are arranged along the entire longitudinal extent of the reservoir 2, so that the module 1 in the case of a single-row arrangement according to Figure 6A has a total of 625 nozzle channels 6 and according to in the case of the two-row arrangement Figure 6B a total of 1250 nozzle channels 6.

The module 1 is designed to be sufficiently stable to withstand the excess pressure with which the viscous medium is applied in the reservoir 2 in order to let it out of the reservoir 2 through the nozzle channels 6. Typically, depending on the viscosity of the viscous medium and the size of the pressure drop in the nozzle channels 6, an excess pressure of more than 2 bar is used, typically the excess pressure is in a range between 2 bar and 30 bar. The viscous medium used typically has a (dynamic) Viscosity of 0.5 Pa · s or more and can for example be present as a paste. As a rule, however, the viscosity is not more than 150 Pa · s.

Figure 7 shows a highly schematic and a side view of a specific example of a system 12 of the type proposed here for producing a microstructure on a surface 16 of a component 17, for example on an aerofoil or a fuselage of an aircraft. The system 12 comprises a module 1 of the type proposed here, such as that in FIG Figure 1 Module 1 is shown, as well as a controllable conveying device 13 which is set up to convey the viscous medium via two media lines 14 (only one is in Figure 7 shown), which are connected to the media connections 3 of the module 1, to be conveyed into the reservoir 2 of the module 1 and to be acted upon there with a sufficiently high overpressure in order to discharge it from the reservoir 2 of the module 1 through the nozzle channels 6. The system 12 does not include any movable closing elements which are arranged on the nozzle channels 6 and which would be set up to open and close the nozzle channels.

• zum Starten eines Auftragevorgangs und zum Aufrechterhalten des Auftragevorgangs die Fördervorrichtung 13 so anzusteuern, dass die Fördervorrichtung 13 das viskose Medium innerhalb das Reservoirs 2 mit dem genannten Überdruck beaufschlagt, und
• zum Stoppen oder Unterbrechen des Auftragevorgangs die Fördervorrichtung 13 so anzusteuern, dass die Fördervorrichtung 13 durch ein Stoppen der Förderung den Überdruck des viskosen Mediums innerhalb des Reservoirs 2 soweit absenkt, dass der Durchlasswiderstand der Düsenkanäle 6 das Ausströmen des viskosen Mediums durch die Düsenkanäle 6 stoppt.

A control unit 15 of the system 12 is set up for this

• to start an application process and to maintain the application process, to control the conveying device 13 such that the conveying device 13 acts on the viscous medium within the reservoir 2 with the above-mentioned pressure, and
• to stop or interrupt the application process, control the conveying device 13 such that the conveying device 13 lowers the overpressure of the viscous medium within the reservoir 2 by stopping the conveying so that the flow resistance of the nozzle channels 6 stops the outflow of the viscous medium through the nozzle channels 6.

The system 12 also comprises a flexible die 18 designed as an endless belt with a negative of the microstructure to be produced. The matrix 18 and the module 1 are arranged such that the viscous medium, in Figure 7 shown and provided with the reference numeral 19, applied to the negative of the die 18 by means of the module 1 and made uniform there by means of the doctor edge 7 and introduced into depressions of the negative. The system 12 further comprises two pressure rollers 21 that can be rolled over the surface 16 of the component 17 for pressing the die 18 onto the component surface 16, the pressure rollers 21 and the die 18 being arranged such that when the pressure rollers 21 roll over the component surface 16, the die 18 moves in a rolling movement between the pressure rollers 21 and the surface 16, so that the negative of the die 18 faces the surface 16 is. The system 12 further comprises a deflecting roller 22 which is arranged to deflect and tension the die 18. In order to move the system 12 over the surface 16 of the component 17 and to press the pressure rollers 21 against the surface 16 and to roll them over them (in the direction of FIGS Figure 7 arrows), the system 12 is connected to a correspondingly configured robot arm 23.

The system 12 can thus be used to produce the microstructure on the surface 16 of the component 17 by molding the negative of the die 18. The viscous medium 19 is applied to the negative of the die 18 by means of the module 1 and then applied to the component surface 16 by means of the die 18 by the rolling movement described above. A layer 20 of the viscous medium 19 is generated on the component surface 16. Because the die with the negative is pressed onto the component surface 16 and unrolled, the microstructure to be produced is transferred to the layer 20 by molding the negative by means of the negative of the die 18, while the layer 20 is transferred between the component surface 16 and the negative the die 18 is located. In addition, the viscous medium 19 in the layer 20, while it is still between the die 18 and the component surface 16, is used by means of a device 24 for accelerating the curing, which can have, for example, a UV radiation source and a heat source, which acts on the layer 20 through the permeable matrix 18. The viscous medium 19 can be, for example, dual-cure lacquer. Further details can be found on the DE 103 46 124 B4 and the WO 2005/030472 A1 be removed.

The microstructure is, for example, a riblet structure with rib-like elevations, the heights and spacings of which are, for example, between 50 μm and 0.5 μm.

In Figure 8 A cross section of a mold 25 is shown, which is designed to form the in FIG Figure 1 Module 1 shown by means of an injection molding process to manufacture. The molding tool 25 is designed as a negative form of the module 1 and comprises a two-part die 26 and a two-part core 27. The die 26 has an inner space 28 which is a negative form of the outer surface 4 of the module 1. The core 27 is a negative form of the reservoir 2 of the module 1. A first part 29 of the core 27 has a large number of pins 30, which are negative forms of the nozzle channels 6 of the module 1. In the manufacture of module 1, a plastic that is suitable for injection molding in a flowable state is fed into the interior 28 of the die 26 through an inlet channel 31 of the assembled molding tool 25. After the plastic has hardened in the molding tool 25, a second part 32 of the core 27 can first be moved out of the reservoir 2 of the hardened module 1. The first part 29 of the core 27 can then also be moved out of the reservoir 2 of the hardened module 1 by utilizing the free space thus created.

Reference symbol list:

1

module

2nd

reservoir

3rd

Media connection

4th

Outside surface

5

Outlet area

6

Nozzle channel

7

Squeegee edge

8th

End cap

9

Intermediate segment

10th

Inlet opening

11

Outlet opening

12

system

13

Conveyor

14

Media management

15

Control unit

16

surface

17th

Component

18th

die

19th

viscous medium

20th

layer

21st

Pressure roller

22

Deflection roller

23

Robotic arm

24th

Device for accelerating the hardening of the viscous medium

25th

Molding tool

26

Die (die part) of the mold

27th

Core of the mold

28

inner space

29

first part of the core

30th

Cones

31

Inlet duct

32

second part of the core

L

Longitudinal axis of the module

d _min

smallest diameter

d _max

largest diameter

I.

Channel length

K ₁

inscribed circle

K ₂

circumscribed circle

Claims (11)

1. A method for depositing a viscous medium, in particular an adhesive or lacquer, onto a surface (16) using a module (1) for depositing the viscous medium (19), wherein the module (1) comprises a reservoir (2) which can be fed with the viscous medium (19), an outer surface (4) of the module (1) comprising an outlet region (5) for the viscous medium (19), wherein the module (1) comprises at least one nozzle channel (6) which fluidically connects the reservoir (2) to the outlet region (5), a smallest diameter (d_min) of the at least one nozzle channel (6) being smaller than 0.8 mm and wherein the module (1) comprises no moving parts for the closure of the at least one nozzle channel (6)and the module (1) comprising a doctor edge (7) which runs along the outlet region, for distributing the viscous medium (19) on the surface (16), wherein

   a discharge of the viscous medium (19) out of the reservoir (2) through the at least one nozzle channel (6) of the module (1) is begun and is maintained, by way of an overpressure of the viscous medium (19) in the reservoir (2) being increased at least until a passage resistance of the at least one nozzle channel (6) to the viscous medium (19) is overcome,

   the discharge of the viscous medium (19) is stopped or interrupted without closing the at least one nozzle channel (6), by way of the overpressure of the viscous medium (19) within the reservoir (2) being reduced at least until the passage resistance of the at least one nozzle channel (6) is no longer overcome,

   the viscous medium (19) is distributed on the surface or introduced into deepenings of the surface using the doctor edge (7) of the module (1), and

   a die (18) with a negative of a microstructure is provided, wherein the viscous medium (19) is deposited onto the negative or onto the component surface by way of the module (1), and the die (18) with the negative is pressed onto the component surface, so that a layer (20) of the viscous medium (19) which comprises the microstructure is created on the component surface.
2. The method according to claim 1, characterized in that an adhesive, a lacquer, or a paint is used as a viscous medium (19) and/or the viscous medium (19) has a viscosity between 0.5 Pa·s and 150 Pa·s.
3. A system (12) for depositing a viscous medium (19), onto a surface, in particular for carrying out a method according to any one of the claims 1 or 2, wherein the system (12) comprises a module (1) for depositing the viscous medium (19) and a delivery device (13) fluidically connectable to the module (1), wherein the module (1) comprises a reservoir (2) which can be fed with the viscous medium (19), an outer surface (4) of the module (1) comprising an outlet region (5) for the viscous medium (19), wherein the module (1) comprises at least one nozzle channel (6) which fluidically connects the reservoir (2) to the outlet region (5), a smallest diameter (d_min) of the at least one nozzle channel (6) being smaller than 0.8 mm and wherein the module (1) comprises no moving parts for the closure of the at least one nozzle channel (6) and the module (1) comprises a doctor edge (7) which runs along the outlet region, for distributing the viscous medium (19) on the surface (16), wherein the delivery device (13) is designed for delivering the viscous medium (19) into the reservoir (2) of the module (1) and for subjecting the viscous medium (19) in the reservoir (2) to an overpressure, the overpressure of the viscous medium (19) in the reservoir (2) which can be produced by way of the delivery device (13) being sufficiently large such that the viscous medium (19) subjected to the overpressure flows out of the reservoir (2) through the at least one nozzle channel (6), wherein the system (12) for manufacturing a microstructure on a component surface moreover comprises:

   a die (18) with a negative of the microstructure to be produced, wherein the die (18) and the module (1) are arranged such that the viscous medium (19) can be deposited by way of the module (1) onto the negative of the die (18) or directly onto the component surface,

   a pressing roller which can roll over the component surface, for pressing the die (18) onto the component surface, the pressing roller and the die (18) being arranged such that on rolling the roller over the component surface, the die (18) is brought into a rolling movement between the pressing roller and the component surface, so that the negative of the die (18) faces the component surface.
4. The system (12) according to claim 3, characterized in that the delivery device (13) is controllable and the system (12) comprises a control unit (15) for the control of the delivery device (13), wherein the control unit (15) is connected to the delivery device (13) for the transmission of control signals, and is configured

   to control the delivery device (13) to apply to the viscous medium (19) within a reservoir (2) an overpressure which is adequately large such that the viscous medium (19) subjected to the overpressure flows out of the reservoir (2) through the at least one nozzle channel (6), for starting a depositing procedure and for maintaining the depositing procedure, and

   to control the delivery device (13) such that the delivery device (13) reduces the overpressure of the viscous medium (19) within the reservoir (2) to such an extent that a passage resistance of the at least one nozzle channel (6) stops the outflow of the viscous medium (19), for stopping the depositing procedure.
5. The system (12) according to any one of the claims 3 or 4, characterized in that the at least one nozzle channel (6) includes several nozzle channels (6) which are arranged in at least one row, wherein the at least one row of nozzle channels (6) runs along a longitudinal extension of the reservoir (2).
6. A system (12) according to any one of the claims 3 to 5, characterized in that the at least one nozzle channel (6) has a channel length (I) which is measured from the reservoir (2) up to the outlet region (5), wherein the channel length (I) is at least 0.8 mm and/or that a largest diameter (d_max) of the nozzle channel (6) is smaller than 3 mm and/or that the at least one nozzle channel (6) tapers towards the outlet region (5), wherein the at least one nozzle channel (6) is preferably designed in a step-like or conical manner.
7. The system (12) according to any one of the claims 3 to 6, characterized in that the reservoir (2) is a cavity of the module (1) which is shaped in an essentially cylindrical manner and/or that the module (1) is designed to withstand a pressure subjection of the viscous medium (19) in the reservoir (2) of 1.5 bar or more.
8. A system (12) according to any one of the claims 3 to 7, characterized in that the doctor edge (7) is arranged on the outer surface (4) of the module (1).
9. The system (12) according to any one of the claims 3 to 8, inasmuch as this refers back to claim 5, characterized in that the nozzle channels (6) are arranged in at least two rows, wherein the at least two rows run next to one another along the longitudinal extension of the reservoir (2), wherein the nozzle channels (6) of the at least two rows are preferably arranged offset to one another in the direction of the longitudinal extension of the reservoir (2).
10. The system (12) according to any one of the claims 3 to 9, characterized in that the module (1) is an injection-molded part manufactured of plastic.
11. The system (12) according to claim 10, characterized in that the doctor edge (7) is a part-region of the injection-molded part which is formed from plastic.

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